import collections


class Solution(object):
    def isPossible(self, nums):
        """
        :type nums: List[int]
        :rtype: bool
        """
        P = []
        P.append(collections.deque([1]))
        for i in range(1, len(nums)):
            if nums[i] == nums[i - 1]:
                P[-1][-1] += 1
            else:
                if nums[i] == nums[i - 1] + 1:
                    P[-1].append(1)
                else:
                    P.append(collections.deque([1]))
        for D in P:
            last = 0
            length = 0
            index = 0
            while D:
                if index == len(D):
                    if length < 3:
                        return False
                    else:
                        length = 0
                        index = 0
                if length == 0:
                    length = 1
                    last = D[index]
                    if D[index] == 1:
                        D.popleft()
                    else:
                        D[index] -= 1
                        index += 1
                else:
                    if D[index] >= last:
                        last = D[index]
                        length += 1
                        if D[index] == 1:
                            D.popleft()
                        else:
                            D[index] -= 1
                            index += 1
                    else:
                        if length < 3:
                            return False
                        else:
                            length = 0
                            index = 0
            if length < 3:
                return False
        return True


data = Solution()
# nums = [1, 2, 3, 3, 4, 4, 5, 5]
# print(data.isPossible(nums))
# nums = [1, 2, 3, 4, 4, 5]
# print(data.isPossible(nums))
# nums = [1, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 6]
# print(data.isPossible(nums))
# nums = [1, 2, 3, 4, 6, 7, 8, 9, 10, 11]
# print(data.isPossible(nums))
nums = [18, 18, 19, 19, 20, 20, 20, 21, 21, 21, 22, 22, 22, 23, 23, 23, 24, 24, 24, 24, 25, 25, 25, 25, 26, 26, 26, 26,
        27, 27, 27, 27, 28, 28, 28, 28, 29, 29, 29, 30, 30, 30, 31, 31, 31, 32, 32, 32, 33, 33, 33, 34, 34, 34, 35, 35,
        35, 36, 36, 36, 37, 37, 37, 38, 38, 38, 39, 39, 39, 40, 40, 40, 41, 41, 41, 42, 42, 43, 43, 44, 44, 45, 45, 46,
        46, 47, 47, 47, 48, 48, 48, 49, 49, 49, 50, 50, 50, 51, 51, 51, 52, 52, 52, 53, 53, 53, 54, 54, 54, 55, 55, 55,
        56, 56, 56, 57, 57, 57, 58, 58, 58, 59, 59, 59, 60, 60, 60, 61, 61, 61, 62, 62, 62, 62, 63, 63, 63, 63, 64, 64,
        64, 64, 65, 65, 65, 65, 65, 66, 66, 66, 66, 66, 67, 67, 67, 67, 67, 68, 68, 68, 68, 68, 68, 69, 69, 69, 69, 69,
        69, 70, 70, 70, 70, 70, 70, 71, 71, 71, 71, 71, 71, 72, 72, 72, 72, 72, 72, 73, 73, 73, 73, 73, 73, 74, 74, 74,
        74, 74, 74, 75, 75, 75, 75, 75, 75, 76, 76, 76, 76, 76, 76, 77, 77, 77, 77, 77, 77, 78, 78, 78, 78, 78, 78, 79,
        79, 79, 79, 79, 79, 80, 80, 80, 80, 80, 80, 80, 81, 81, 81, 81, 81, 81, 81, 82, 82, 82, 82, 82, 82, 82, 83, 83,
        83, 83, 83, 83, 83, 84, 84, 84, 84, 84, 84, 84, 85, 85, 85, 85, 85, 85, 85, 86, 86, 86, 86, 86, 86, 86, 86, 87,
        87, 87, 87, 87, 87, 87, 87, 88, 88, 88, 88, 88, 88, 88, 88, 89, 89, 89, 89, 89, 89, 89, 89, 90, 90, 90, 90, 90,
        90, 90, 90, 91, 91, 91, 91, 91, 91, 91, 92, 92, 92, 92, 92, 92, 92, 93, 93, 93, 93, 93, 93, 93, 94, 94, 94, 94,
        94, 94, 95, 95, 95, 95, 95, 95, 96, 96, 96, 96, 96, 96, 97, 97, 97, 97, 97, 97, 98, 98, 98, 98, 98, 98, 99, 99,
        99, 99, 99, 99, 100, 100, 100, 100, 100, 101, 101, 101, 101, 101, 102, 102, 102, 102, 102, 103, 103, 103, 103,
        103, 104, 104, 104, 104, 104, 105, 105, 105, 105, 105, 106, 106, 106, 106, 106, 107, 107, 107, 107, 107, 108,
        108, 108, 108, 108, 109, 109, 109, 109, 109, 110, 110, 110, 110, 110, 111, 111, 111, 111, 111, 112, 112, 112,
        113, 113, 113, 114, 114, 114, 115, 115, 115, 116, 116, 116, 117, 117, 117, 118, 118, 118, 119, 119, 119, 120,
        120, 120, 121, 121, 121, 122, 122, 122, 123, 123, 123, 124, 124, 124, 125, 125, 125, 126, 126, 126, 127, 127,
        127, 128, 128, 128, 129, 129, 129, 130, 130, 130, 131, 131, 131, 132, 132, 132, 133, 133, 133, 134, 134, 135,
        135, 136, 136, 137, 138, 139]
print(data.isPossible(nums))
